PROJECT SUMMARY Dementia is the most expensive medical condition in the US. There is an urgent need to intervene to curb the increasing prevalence of dementia in our population. Research demonstrates that computerized, cognitive speed of processing training (SPT) improves cognition and transfers to improved instrumental activities of daily living. However, an unanswered question is whether SPT can be successfully implemented to decrease incidence of mild cognitive impairment (MCI) or dementia. Analyses of 10-year data from the ACTIVE trial revealed that older adults randomized to SPT were 29% less likely to develop dementia. Moreover, those who completed additional training had a 48% reduced risk of dementia over 10 years. Two major limitations of this exciting study was a lack of clinical diagnosis of dementia and use of a no-contact control condition. The proposed field trial will advance prior research by implementing SPT in a large population of cognitively normal older adults in Florida. Older adults will be randomized to SPT or an active control condition of cognitive stimulation (i.e., computer games) and progression to MCI or dementia will be clinically assessed over time. We further will determine if SPT effects are specific for those with/without amyloid pathology or Apolipoprotein E4, and quantify the effects of SPT on subsequent healthcare costs and utilization. Leveraging our existing Community-Based Memory Screening program, we will identify and enroll a diverse sample of thousands (N=7600) of older adults without evidence of cognitive impairment who can potentially benefit from SPT over 3 years. We have already screened ~5000 individuals in this program, which will be expanded for the proposed study. Our primary goal will be to examine the effectiveness of SPT to reduce incidence of MCI or dementia. After 3 years, we will begin repeating memory screenings of participants to identify those exhibiting cognitive decline. Such participants will be provided a thorough medical evaluation to clinically ascertain MCI or dementia. Participants will complete genetic testing and receive an amyloid PET scan to further determine the cause of cognitive decline. Given the 7-year funding period, our sample size will yield a sufficient number of diagnosed MCI/dementia cases within the last four years of the study. The primary contribution of the proposed research will be the determination of whether SPT successfully reduces incidence of MCI and/or dementia. This contribution will be significant in that if an intervention could delay the onset of Alzheimer's disease by only one year, there would be ~9.2 million fewer cases of the disease in 2050, substantially reducing costs. Results will inform subsequent research and clinical practice by facilitating implementation of effective interventions to attenuate cognitive and functional decline and thereby improve public health.